5fc469ad98
- Introduced `VexStatusChipComponent` to display VEX status with color coding and tooltips. - Implemented integration tests for reachability drift detection, covering various scenarios including drift detection, determinism, and error handling. - Enhanced `ScannerToSignalsReachabilityTests` with a null implementation of `ICallGraphSyncService` for better test isolation. - Updated project references to include the new Reachability Drift library.
473 lines
14 KiB
Markdown
473 lines
14 KiB
Markdown
# Reachability Input Contract v1.0.0
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**Status:** APPROVED
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**Version:** 1.0.0
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**Effective:** 2025-12-19
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**Owner:** Policy Guild + Signals Guild
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**Sprint:** SPRINT_0126_0001_0001 (unblocks POLICY-ENGINE-80-001 through 80-004)
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---
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## 1. Purpose
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This contract defines the integration between the Signals service (reachability analysis) and the Policy Engine. It specifies how reachability and exploitability facts flow into policy evaluation, enabling risk-aware decisions based on static analysis, runtime observations, and exploit intelligence.
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## 2. Schema Reference
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The canonical JSON schema is at:
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```
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docs/schemas/reachability-input.schema.json
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```
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## 3. Data Flow
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```
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┌─────────────┐ ┌──────────────┐ ┌───────────────┐ ┌──────────────┐
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│ Scanner │────▶│ Signals │────▶│ Reachability │────▶│ Policy │
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│ (callgraph) │ │ Service │ │ Facts Store │ │ Engine │
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└─────────────┘ └──────────────┘ └───────────────┘ └──────────────┘
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│ ▲
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│ │
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┌──────▼──────┐ │
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│ Runtime │──────────────┘
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│ Agent │
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└─────────────┘
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```
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## 4. Core Types
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### 4.1 ReachabilityInput
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The input payload submitted to Policy Engine for evaluation:
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```csharp
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public sealed record ReachabilityInput
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{
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/// <summary>Subject being evaluated (component + vulnerability).</summary>
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public required Subject Subject { get; init; }
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/// <summary>Static reachability analysis results.</summary>
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public required ImmutableArray<ReachabilityFact> ReachabilityFacts { get; init; }
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/// <summary>Exploitability assessments from KEV, EPSS, vendor advisories.</summary>
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public ImmutableArray<ExploitabilityFact> ExploitabilityFacts { get; init; }
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/// <summary>References to stored callgraphs.</summary>
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public ImmutableArray<CallgraphRef> CallgraphRefs { get; init; }
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/// <summary>Runtime observation facts.</summary>
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public ImmutableArray<RuntimeFact> RuntimeFacts { get; init; }
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/// <summary>Scanner entropy/trust score for confidence weighting.</summary>
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public EntropyScore? EntropyScore { get; init; }
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/// <summary>Input timestamp (UTC).</summary>
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public required DateTimeOffset Timestamp { get; init; }
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}
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```
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### 4.2 Subject
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```csharp
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public sealed record Subject
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{
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/// <summary>Package URL of the component.</summary>
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public required string Purl { get; init; }
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/// <summary>CVE identifier (e.g., CVE-2024-1234).</summary>
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public string? CveId { get; init; }
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/// <summary>GitHub Security Advisory ID.</summary>
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public string? GhsaId { get; init; }
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/// <summary>Internal vulnerability identifier.</summary>
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public string? VulnerabilityId { get; init; }
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/// <summary>Vulnerable symbols/functions in the component.</summary>
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public ImmutableArray<string> AffectedSymbols { get; init; }
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/// <summary>Affected version range (e.g., "<1.2.3").</summary>
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public string? VersionRange { get; init; }
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}
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```
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### 4.3 ReachabilityFact
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```csharp
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public sealed record ReachabilityFact
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{
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/// <summary>Reachability state determination.</summary>
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public required ReachabilityState State { get; init; }
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/// <summary>Confidence score (0.0-1.0).</summary>
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public required decimal Confidence { get; init; }
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/// <summary>Source of determination.</summary>
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public required ReachabilitySource Source { get; init; }
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/// <summary>Analyzer that produced this fact.</summary>
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public string? Analyzer { get; init; }
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/// <summary>Analyzer version.</summary>
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public string? AnalyzerVersion { get; init; }
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/// <summary>Call path from entry point to vulnerable symbol.</summary>
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public CallPath? CallPath { get; init; }
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/// <summary>Entry points that can reach vulnerable code.</summary>
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public ImmutableArray<EntryPoint> EntryPoints { get; init; }
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/// <summary>Supporting evidence.</summary>
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public ReachabilityEvidence? Evidence { get; init; }
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/// <summary>When this fact was evaluated.</summary>
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public DateTimeOffset? EvaluatedAt { get; init; }
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}
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public enum ReachabilityState
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{
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Reachable = 0,
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Unreachable = 1,
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PotentiallyReachable = 2,
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Unknown = 3
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}
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public enum ReachabilitySource
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{
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StaticAnalysis = 0,
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DynamicAnalysis = 1,
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SbomInference = 2,
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Manual = 3,
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External = 4
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}
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```
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### 4.4 ExploitabilityFact
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```csharp
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public sealed record ExploitabilityFact
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{
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/// <summary>Exploitability state.</summary>
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public required ExploitabilityState State { get; init; }
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/// <summary>Confidence score (0.0-1.0).</summary>
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public required decimal Confidence { get; init; }
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/// <summary>Source of determination.</summary>
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public required ExploitabilitySource Source { get; init; }
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/// <summary>EPSS probability score (0.0-1.0).</summary>
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public decimal? EpssScore { get; init; }
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/// <summary>EPSS percentile (0-100).</summary>
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public decimal? EpssPercentile { get; init; }
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/// <summary>Listed in CISA Known Exploited Vulnerabilities.</summary>
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public bool? KevListed { get; init; }
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/// <summary>KEV remediation due date.</summary>
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public DateOnly? KevDueDate { get; init; }
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/// <summary>Exploit maturity level (per CVSS).</summary>
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public ExploitMaturity? ExploitMaturity { get; init; }
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/// <summary>References to known exploits.</summary>
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public ImmutableArray<Uri> ExploitRefs { get; init; }
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/// <summary>Conditions required for exploitation.</summary>
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public ImmutableArray<ExploitCondition> Conditions { get; init; }
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/// <summary>When this fact was evaluated.</summary>
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public DateTimeOffset? EvaluatedAt { get; init; }
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}
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public enum ExploitabilityState
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{
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Exploitable = 0,
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NotExploitable = 1,
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ConditionallyExploitable = 2,
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Unknown = 3
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}
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public enum ExploitabilitySource
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{
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Kev = 0,
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Epss = 1,
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VendorAdvisory = 2,
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InternalAnalysis = 3,
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ExploitDb = 4
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}
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public enum ExploitMaturity
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{
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NotDefined = 0,
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Unproven = 1,
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Poc = 2,
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Functional = 3,
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High = 4
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}
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```
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### 4.5 RuntimeFact
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```csharp
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public sealed record RuntimeFact
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{
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/// <summary>Type of runtime observation.</summary>
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public required RuntimeFactType Type { get; init; }
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/// <summary>Observed symbol/function.</summary>
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public string? Symbol { get; init; }
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/// <summary>Observed module.</summary>
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public string? Module { get; init; }
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/// <summary>Number of times called.</summary>
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public int? CallCount { get; init; }
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/// <summary>Last invocation time.</summary>
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public DateTimeOffset? LastCalled { get; init; }
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/// <summary>When observation was recorded.</summary>
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public required DateTimeOffset ObservedAt { get; init; }
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/// <summary>Observation window duration (e.g., "7d").</summary>
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public string? ObservationWindow { get; init; }
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/// <summary>Environment where observed.</summary>
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public RuntimeEnvironment? Environment { get; init; }
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}
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public enum RuntimeFactType
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{
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FunctionCalled = 0,
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FunctionNotCalled = 1,
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PathExecuted = 2,
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PathNotExecuted = 3,
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ModuleLoaded = 4,
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ModuleNotLoaded = 5
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}
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public enum RuntimeEnvironment
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{
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Production = 0,
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Staging = 1,
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Development = 2,
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Test = 3
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}
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```
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## 5. Policy Engine Integration
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### 5.1 ReachabilityFactsJoiningService
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The `ReachabilityFactsJoiningService` provides efficient batch lookups with caching:
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```csharp
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public interface IReachabilityFactsJoiningService
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{
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/// <summary>
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/// Gets reachability facts for a batch of component-advisory pairs.
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/// Uses cache-first strategy with store fallback.
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/// </summary>
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Task<ReachabilityFactsBatch> GetFactsBatchAsync(
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string tenantId,
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IReadOnlyList<ReachabilityFactsRequest> items,
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CancellationToken cancellationToken = default);
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/// <summary>
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/// Enriches signal context with reachability facts.
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/// </summary>
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Task<bool> EnrichSignalsAsync(
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string tenantId,
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string componentPurl,
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string advisoryId,
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IDictionary<string, object?> signals,
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CancellationToken cancellationToken = default);
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}
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```
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### 5.2 SPL Predicates
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Reachability is exposed in SPL (StellaOps Policy Language) via the `reachability` scope:
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```yaml
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# Example SPL rule using reachability predicates
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rules:
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- name: "Suppress unreachable critical CVEs"
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when:
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all:
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- severity >= critical
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- reachability.state == "unreachable"
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- reachability.confidence >= 0.9
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then:
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effect: suppress
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justification: "Unreachable code path with high confidence"
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- name: "Escalate reachable with exploit"
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when:
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all:
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- reachability.state == "reachable"
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- exploitability.kev_listed == true
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then:
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effect: escalate
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priority: critical
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```
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Available predicates:
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| Predicate | Type | Description |
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|-----------|------|-------------|
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| `reachability.state` | string | "reachable", "unreachable", "potentially_reachable", "unknown" |
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| `reachability.confidence` | decimal | Confidence score 0.0-1.0 |
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| `reachability.score` | decimal | Computed risk score |
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| `reachability.has_runtime_evidence` | bool | Whether runtime facts support determination |
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| `reachability.is_high_confidence` | bool | Confidence >= 0.8 |
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| `reachability.source` | string | Source of determination |
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| `reachability.method` | string | Analysis method used |
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| `exploitability.state` | string | "exploitable", "not_exploitable", "conditionally_exploitable", "unknown" |
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| `exploitability.epss_score` | decimal | EPSS probability 0.0-1.0 |
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| `exploitability.epss_percentile` | decimal | EPSS percentile 0-100 |
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| `exploitability.kev_listed` | bool | In CISA KEV catalog |
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| `exploitability.kev_due_date` | date | KEV remediation deadline |
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| `exploitability.maturity` | string | "not_defined", "unproven", "poc", "functional", "high" |
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### 5.3 ReachabilityOutput
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Policy evaluation produces enriched output:
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```csharp
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public sealed record ReachabilityOutput
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{
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/// <summary>Subject evaluated.</summary>
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public required Subject Subject { get; init; }
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/// <summary>Effective reachability state after policy rules.</summary>
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public required ReachabilityState EffectiveState { get; init; }
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/// <summary>Effective exploitability after policy rules.</summary>
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public ExploitabilityState? EffectiveExploitability { get; init; }
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/// <summary>Risk adjustment from policy evaluation.</summary>
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public required RiskAdjustment RiskAdjustment { get; init; }
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/// <summary>Policy rule trace.</summary>
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public ImmutableArray<PolicyRuleTrace> PolicyTrace { get; init; }
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/// <summary>When evaluation occurred.</summary>
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public required DateTimeOffset EvaluatedAt { get; init; }
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}
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public sealed record RiskAdjustment
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{
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/// <summary>Risk multiplier (0=suppress, 1=neutral, >1=amplify).</summary>
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public required decimal Factor { get; init; }
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/// <summary>Severity override if rules dictate.</summary>
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public Severity? SeverityOverride { get; init; }
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/// <summary>Justification for adjustment.</summary>
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public string? Justification { get; init; }
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}
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```
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## 6. API Endpoints
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### 6.1 Signals Service Endpoints
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| Endpoint | Method | Description |
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|----------|--------|-------------|
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| `POST /signals/reachability/recompute` | POST | Recompute reachability for a subject |
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| `GET /signals/facts/{subjectKey}` | GET | Get reachability facts for a subject |
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| `POST /signals/runtime-facts` | POST | Ingest runtime observations |
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### 6.2 Policy Engine Endpoints
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| Endpoint | Method | Description |
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|----------|--------|-------------|
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| `POST /api/policy/evaluate` | POST | Evaluate with reachability enrichment |
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| `POST /api/policy/simulate` | POST | Simulate with reachability overrides |
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| `GET /api/policy/reachability/stats` | GET | Get reachability integration metrics |
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## 7. Caching Strategy
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### 7.1 Cache Layers
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1. **L1: In-Memory Overlay Cache**
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- Per-request deduplication
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- TTL: Request lifetime
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- Key: `{tenantId}:{componentPurl}:{advisoryId}`
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2. **L2: Redis Distributed Cache**
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- Shared across Policy Engine instances
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- TTL: 5 minutes (configurable)
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- Key: `rf:{tenantId}:{sha256(purl+advisoryId)}`
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3. **L3: Postgres Facts Store**
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- Authoritative source
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- Indexed by `(tenant_id, component_purl, advisory_id)`
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### 7.2 Cache Invalidation
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- Facts are invalidated when:
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- New callgraph is ingested
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- Runtime facts are updated
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- Manual override is applied
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- TTL expires
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## 8. Telemetry
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### 8.1 Metrics
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| Metric | Type | Labels | Description |
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|--------|------|--------|-------------|
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| `policy_reachability_applied_total` | counter | `state` | Facts applied to evaluations |
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| `policy_reachability_cache_hits_total` | counter | - | Cache hits |
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| `policy_reachability_cache_misses_total` | counter | - | Cache misses |
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| `policy_reachability_cache_hit_ratio` | gauge | - | Hit ratio (0.0-1.0) |
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| `policy_reachability_lookups_total` | counter | `outcome` | Lookup attempts |
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| `policy_reachability_lookup_seconds` | histogram | - | Lookup latency |
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### 8.2 Traces
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Activity: `reachability_facts.batch_lookup`
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Tags:
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- `tenant`: Tenant ID
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- `batch_size`: Number of items requested
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- `cache_hits`: Items found in cache
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- `cache_misses`: Items not in cache
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- `store_hits`: Items fetched from store
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## 9. Configuration
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```yaml
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# etc/policy-engine.yaml
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PolicyEngine:
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Reachability:
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Enabled: true
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CacheTtlSeconds: 300
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MaxBatchSize: 1000
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DefaultConfidenceThreshold: 0.7
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HighConfidenceThreshold: 0.9
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ReachabilityCache:
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Type: "redis" # or "memory"
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RedisConnectionString: "${REDIS_URL}"
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KeyPrefix: "rf:"
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```
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## 10. Validation Rules
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1. `Subject.Purl` must be a valid Package URL
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2. `ReachabilityFact.Confidence` must be 0.0-1.0
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3. `ReachabilityFact.State` must be a valid enum value
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4. `Timestamp` must be valid UTC ISO-8601
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5. At least one of `CveId`, `GhsaId`, or `VulnerabilityId` must be present
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---
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## Changelog
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| Version | Date | Changes |
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|---------|------|---------|
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| 1.0.0 | 2025-12-19 | Initial release |
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